Constantine IV (Greek: Κωνσταντῖνος Δ', Latin: Flavius Constantinus Augustus), sometimes incorrectly called Pogonatos, "the Bearded", out of confusion with his father, was Byzantine Emperor from 668 to 685. His reign saw the first serious check to nearly 50 years of uninterrupted Islamic expansion, while his calling of the Sixth Ecumenical Council saw the end of the monothelitism controversy in the Byzantine Empire.